I've been doing a lot of reading about compressing your servers output stream.
Before gzip compression, the bink.nu homepage was about 321k! This means that it would take about 89 seconds for a normal 56k user to download the page.
After gzip compression, the page is 79k! Now it takes the same 56k user 22 seconds to download the page.
If your server can support a little extra load (to compress the output stream), then I highly reccomend using a output stream compression engine!
Here is a list of .NET/ISAPI (for IIS) modules that I'm aware of:
.NET Modules
ASPAccelerator.NET
http://www.intesoft.net/aspaccelerator/
Blowery HttpCompression Module
http://www.blowery.org/code/HttpCompressionModule.html
ISAPI Filters
XCompress
http://www.xcompress.com/
IIS Accelerator
http://www.iisaccelerator.com/
SqueezePlay
http://www.innermedia.com/
jetNEXUS for IIS
http://www.preactholdings.com/performance/products/jetnexus/jet-nexus/
PipeBoost
http://www.pipeboost.com/
TurboIIS Pro
http://www.objectsfarm.com/turboiis/
Maybe someone can post some good ones for Apache..